1. Field of the Invention
The present invention relates to a lens barrel provided with a vibration actuator and to a camera.
2. Related Art
A vibration actuator, as disclosed in Patent Document 1, generates a progressive vibration wave (below abbreviated as “progressive wave”) at a driving face of an elastic body utilizing the expansion and contraction of a piezoelectric body. An elliptic motion is generated at the driving face by this progressive wave, and wave crests of the elliptic motion drive a moving element which is in pressure contact with the wave crests. Such a vibration actuator has the characteristic of having a high torque even at a low revolution rate. Therefore, when installed in a driving device, the vibration actuator has advantages that it is possible to omit gears of the driving device, so that it is possible to achieve silencing due to lack of gear noise and an increase in the positioning accuracy.
A technique is disclosed in Patent Document 2, which directly drives a lens barrel of a steel camera or an automatically focusing lens (hereinafter referred to as “AF lens”) of an interchangeable lens of an electronic camera, using a linear vibration actuator.
Patent Document 1: Japanese Examined Patent Application No. H1-17354
Patent Document 2: Japanese Unexamined Patent Application No. 2006-187114